The effect of salinity change on the oxygen consumption and swimming activity of the high-shore rockpool copepod Tigriopus brevicornis

Tigriopus brevicornis is the dominant member of the fauna in high-shore roc kpools (above the mean high water of spring tides) that are subject to extr eme environmental variation especially in salinity due to infrequent tidal inundation. The present study was designed to assess the effect of large-sc ale salinity change on the rate of oxygen consumption and levels of activit y. Measurements of the rates of oxygen consumption (V-o2) of T brevicornis in response to simulated changes in salinity (of a magnitude that had previ ously been recorded in high-shore rock pools inhabited by T. brevicornis) w ere carried out using closed respirometry. Activity levels of T. brevicorni s during exposure to three different salinities (10, 33 and 90 psu) were as sessed by means of video image analysis. The study showed that T. brevicorn is exhibits a reduction in activity and in oxygen consumption when exposed to higher salinities. However, individuals exposed to low salinities showed elevated rates of oxygen consumption without an associated increase in act ivity. The present study indicates that animals living in high-shore rockpo ols may incur a considerable energetic cost, due to the rapid and large-sca le environmental changes that are characteristic of this habitat. (C) 2001 Elsevier Science B.V. All rights reserved.